【转】libcurl note（Http应用)

设置Callback function处理Http头，返回内容，进度
CURLOPT_WRITEFUNCTION
CURLOPT_WRITEDATA

CURLOPT_HEADERFUNCTION
CURLOPT_HEADERDATA

CURLOPT_NOPROGRESS
CURLOPT_PROGRESSFUNCTION
CURLOPT_PROGRESSDATA

设置连接等待时间，传输等待时间：
CURLOPT_TIMEOUT:
CURLOPT_CONNECTIONTIMEOUT:

设置重定位URL：
CURLOPT_FOLLOWLOCATION

实现断点续传：
CURLOPT_RANGE:
CURLOPT_RESUME_FROM:
注： 在我的测试中 这两个参数无效。 设置RANGE后 下载全部数据，而不是后续数据;设置RESUME_FROM后，程序无响应。


Http头设置：
Range: bytes=xx-       [可以用来实现断点续传]
User-Agent: xx
Location:              [网页重定位 url]
Set-Cookie:            [Cookie]
Content-Length:        [报文长度]
Content-Type:            [报文类型]


例程：

test() {         CURL *curl;         CURLcode res;         struct curl_slist *slist_header = NULL;                                                                                          FILE *pFile_error = fopen(CURL_ERROR_FILE, "w+");                                                                                          curl = curl_easy_init();         if(curl)         {                 slist_header = curl_slist_append(slist_header, version_id.data());                 curl_easy_setopt(curl, CURLOPT_HTTPHEADER, slist_header);                                                                                                  QString follow_location=QString("With follow location");                 curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, follow_location.data());                 curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout);                 curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, timeout_connect); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);                 curl_easy_setopt(curl, CURLOPT_NOPROGRESS, false);                 curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_callback); curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &progress_percent) ;                               curl_easy_setopt(curl, CURLOPT_WRITEDATA, &recv_buf);                 curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, header_callback); curl_easy_setopt(curl, CURLOPT_HEADERDATA, &header_buf);                 curl_easy_setopt(curl, CURLOPT_POST, TRUE);                 curl_easy_setopt(curl, CURLOPT_POSTFIELDS,zip_buf);                 curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE,zip_len);                 curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);                 curl_easy_setopt(curl, CURLOPT_STDERR, pFile_error);                 int res = curl_easy_perform(curl);                 if (res == 0) {                         .......                 }                 curl_easy_cleanup(curl);                 curl_slist_free_all(slist_header);                 fflush(pFile_error);                 fclose(pFile_error);         } }